Catheters having inflatable balloons affixed to their leading edge are commonly used in a variety of surgical applications. One application for such a "balloon catheter," is for dilating blood vessels which have been partially or entirely blocked by deposits or other obstructions. The balloon catheter is introduced into the affected blood vessel and the deflated balloon is maneuvered into a blocked or otherwise obstructed flow path within the vessel. By inflating the balloon, the deposits or obstructions are compressed against the inner wall of the vessel, thereby enlarging the flow path. Other applications include the removal and/or compression of adherent materials such as atherosclerotic plaque, thrombosis, stenosis, occlusions, clots, stones, and other potentially obstructive material from within vascular conduits and other body passageways.
Prior devices used in such applications include catheters having a catheter shaft and an inflatable balloon located near the leading or distal end of the catheter. The balloon of such a catheter usually consists of an inflatable sleeve or bulb fitted on the outside of the tubular catheter shaft. The balloon is inflated by the infusion of a fluid into the balloon chamber from within the shaft. It is important that the balloon's inflation be controlled, such that it is not overinflated, resulting in an overexpanded balloon which can rupture or otherwise damage the affected vascular conduit or other body conduit.
In an effort to reduce the dangers of over expansion and thus, potential damage to the conduit, modern catheters are commonly configured with reinforced balloons that can only expand to a predetermined maximum diameter, regardless of the interior pressure applied. While effective at limiting the radial expansion of the associated balloon, these catheters are only effective when used within a vascular or other conduit of a specified size. Conduits having different or changing diameters may require the use of a number of such catheters, each having a specified maximum balloon diameter. In addition, many applications could benefit from a balloon having a specific configuration or shape for use within the conduit. These specific shapes or configurations could advantageously be used to compress or remove occluding material, for infusing treatment fluids as well as for therapeutic effects. Thus, there is a need for a balloon catheter which can restrain the maximum radial expansion of the inflated balloon and can also configure the inflated balloon to a specified shape or configuration. There is also a need for such a balloon catheter which has the ability to limit the radial expansion of the inflated balloon to a number of different maximum radial diameters.
When removing occluding material from within a vascular conduit, such as a blood vessel, it is important that the surface of the balloon catheter be relatively smooth in order to prevent damage to the inner lining. Prior art balloon catheters are generally provided with a smooth outer surface for this purpose. However, it is often desirable to have an abrasive outer surface for contacting the inner walls of the vascular conduit. The abrasive outer surface allows for improved removal of the occluding material as well as for traction. In addition, there is also a need for a balloon catheter having a more abrasive outer surface for use in other applications such as the removal of thrombus or other obstructions from within an artificial graft. These applications often require more intense scrubbing. Thus, there is a need for a balloon catheter which has an abrasive outer surface, yet which is not damaging to the inner lining of the vascular conduit or other conduit. There is also a need for such an abrasive outer surface that retains a consistent abrasiveness regardless of the balloon's inflation or expansion. There is also a need for a balloon catheter which includes an abrasive outer surface suitable for removing thrombus or other occluding material from within an artificial graft.